1. Set the oven at 375 degrees. Line a heavy baking sheet with parchment paper.

2. In a large bowl, whisk together the flour, baking powder, salt, and the 3 tablespoons sugar just to blend them.

3. Scatter the butter over the flour mixture. Using a pastry blender or two blunt knives, cut the fat into the flour until it is reduced to pea-size bits.

4. In a small bowl, whisk together the half-and-half, egg, extra yolk, and vanilla. Pour the egg mixture over the flour mixture, scatter the chips on top. With a rubber spatula, stir the mixture to form a dense dough. Knead it lightly in the bowl for 5 to 7 turns.

5. Form the dough into a plump ball about 4 to 5 inches in diameter. Place the ball on the baking sheet and, using a sharp paring knife, slash a shallow “x’’ in the top. Sprinkle the top with extra sugar.

6. Bake the round for 40 minutes or until it sets and turns golden brown. Transfer to a wire rack and cool completely. Use a serrated knife to cut it into wedges.